The goals of the proposed research are to 1. develop methods for disease control in Rana catesbeiana; 2. induce natural or artificial breeding in laboratory-reared bullfrogs and establish defined strains, and 3. establish environmental management techniques for culturing bullfrogs with known physiological conditions. The study will emphasize the following: 1. Evaluate the effects of gonadotropins and other hormones stimulatory to the reproductive system, on different age and size females reared under defined photoperiod and temperature cycles. 2. Attempt to induce natural breeding in the laboratory by subjecting both sexes to recorded male breeding choruses under photoperiod and temperature cycles. 3. Determine whether or not laboratory-reared females can be ovulated with hormones when exposed to recorded breeding choruses under defined photoperiod and temperature cycles. 4. Determine the effects of combinations of photoperiod, temperature and timed disturbances on growth, metamorphosis, food consumption and conversion, nutritional, and bacterial community structure of bullfrog larvae. 5. Isolate and inactivate toxins produced by bacteria known to be pathogenic for frogs. 6. Determine whether or not the intestinal tract can be the source of bacteria or bacterial toxins which could initiate the disease process. 7. Determine the size of the antigen that can be administered to large numbers of larvae and determine the conditions necessary for successful vaccination against septicemic disease of frogs. 8. Continue efforts to establish defined strains of bullfrogs suitable for biomedical research.